The present invention relates to a texturized soy beverage base which includes the soybean hulls and phytonutrients, and to processes for the preparation thereof.
For several decades, particularly in the 1960""s and 1970""s, numerous studies were conducted to discover the chemistry of the formation of beany flavor during the preparation of soy products. It was found that the characteristic flavor of soy milk in particular, and soy products, in general, results mainly from peroxidation of polyunsaturated fatty acids or esters catalyzed by an enzyme known as lipooxygenase (Wilkens et al. 1967; Wilkens and Lin 1970; Nelson et al. 1971, 1976).
The reaction produces many volatile compounds that can be identified by gas chromatography. Most of these volatile compounds are reported to be ketones, aldehydes, and alcohols, and many of them impart undesirable flavor.
Soymilk is a water extract, so, in some processing steps, water must be incorporated into beans. There are several ways to do so. Most commercial as well as traditional methods involve soaking beans overnight until fully hydrated and then grinding the soaked beans with additional fresh water. The benefits of soaking include reducing the power input required for grinding, causing much less wear on the millstones or blades, leaching out some oligosaccharides, enabling better dispersion and suspension of the solids during extraction, decreasing cooking time, and increasing yields.
The disadvantages of soaking include losses of water soluble solids and induction of biological changes. Lo et al. (1968) studied the effects of soaking soybeans before extraction on the chemical composition of leached solids and soymilk made from soaked beans. They found that as the soaking time increased, larger quantities of water soluble solids leached into the soaking water, including nonprotein nitrogen compounds, soluble sugars, and minerals. On the average, soaking beans for 24 hr resulted in a 5% loss, whereas 72-hr soaking led to a 10% loss of solids. They also observed mild metabolic changes as a result of soaking. Regardless of these changes, they found no measurable difference in the gross composition of the soymilks made from beans soaked for 16 hr (overnight) and 72 hr, although they did not compare these milks with that from unsoaked beans. Soaking also induces hydrolysis of isoflavone aglucones to their glucoside forms, resulting in development of objectionable aftertaste of soymilk (Matsuura et al. 1989).
There are methods for bypassing the soaking stage. Some, such as the hot grinding method, accomplish hydration and grinding in one step. Others make soymilk by first grinding dry soybeans and then blending the flour with water. For example, Hand et al. (1964) reported a method involving dehulling and grinding of dried soybeans followed by slurrying the powder with water. The resultant milk contained about 90% of the total solids. Some commercial processors, such as one in Hong Kong which mass-produces Vitasoy and Taishi Foods Ltd. of Japan, follow Hand et al. by using dry-ground soy flour. In addition, Mustakas et al. (1964) developed a process in which dehulled soybean flakes, properly conditioned with moisture, are fed into an extruder cooker, which provides short-time, high-temperature, high-pressure conditions. The cooked, puffed, and dried material is then finely ground and slurred with water to form soymilk.
The water temperature used for soymilk production is another subject of consideration, because it affects the rate of bean hydration, the rate and type of solids leakage, the rate of metabolic changes, and more importantly, the quality of soymilk. The traditional method calls for room temperature soaking followed by cold grinding. In many new methods, however, particularly those bypassing the soaking step, hot water is normally used in conjunction with blanching or grinding. Wilkens and Hackler (1969) studied the effects of soaking temperature and time on rates of water absorption, nutrient losses, and soymilk yields. They found that the higher the temperature, the faster the rate of soybean hydration. Dehulled soybeans reached fall hydration much faster than whole beans, requiring 2 to 3 hr at 30xc2x0 C. or 1 hr at 50xc2x0 C. as compared with 7 hr at 30xc2x0 C. at 50xc2x0 C. for the whole beans. At soaking temperatures above 45xc2x0 C., there was a large decrease in the total solids and carbohydrates recovered in the soymilk and a small decrease in the recovery of protein and fats. The longer the soaking time, the greater the losses. Increasing the temperature of soaking water from 45xc2x0 to 65xc2x0 C. followed by hot grinding resulted in a decrease of about 6% in the volume of soymilk obtained from the dehulled soybeans.
Adding alkaline salts such as sodium bicarbonate (baking soda), sodium carbonate, sodium citrate, or sodium hydroxide to the water has also been shown to affect soymilk quality. Soymilk made from water alone has a pH near neutral (6.5-6.8). When added to water during soaking, blanching, or grinding, alkaline salts raise the pH of, and add ions to, the soybean water extract. As a result, soy protein becomes more soluble in the extract. Protein and solid recovery increase. In addition, alkaline salts have been shown to decrease the beany flavor, help inactivate trypsin inhibitors, reduce oligosaccharides, and tenderize the soybean, which makes such processing steps as grinding, heating, and homogenizing faster and easier. However, there are some disadvantages associated with the use of alkali salts. The addition of salts increases costs and salts may not be available in many rural areas. Because alkaline salts raise the pH of soymilk, the addition of an acid for neutralization may be necessary. More importantly, alkaline salts help destroy some key nutrients during processing, including sulfur-containing amino acids and some vitamins, and thus reduce nutritional quality of soymilk. Alkaline salts also slightly darken soymilk and may impart xe2x80x9csoapyxe2x80x9d flavor (Badenhop and Hackler, 1970, Bourne et al. 1976, Johnson and Snyder (1978).
Although heat treatment has many benefits, extended heating should be avoided, because overheating leads to destruction of such nutrients as essential amino acids and vitamins. Extended heating also alters the functional properties of soy protein to such an extent that they become less coagulated when made into tofu.
In addition to heating temperature and time, the moisture condition prior to and during heat treatment has a significant effect on the effectiveness of TI (trypsin inhibitor) destruction by heat. For example, cooking whole soybeans reduces trypsin inhibitor activity to about 15% of that in raw beans. However, for complete removal of trypsin inhibitors, soaking prior to cooking is necessary, even though soaking has no effects on TI activity (Liu and Markakis 1987).
Based on the activity loss of the purified inhibitors, the Kunitz inhibitor was thought to be more heat labile than the BB inhibitor (Birk 1961). However, DiPietro and Liener (1989) demonstrated that an in situ BB inhibitor is inactivated at a faster rate than the Kunitz inhibitor upon heating.
Heat treatment reduces not only TI activities, but also solubility of the whole seed protein (Anderson 1992). More importantly, excessive heat treatment can cause loss of essential amino acids in soy protein (Rios-Iriarte and Barnes 1966, Skrede and Krogdahl 1985). Therefore, in applying heat to soy products, it is essential to use an optimum condition (temperature, time, moisture, and pressure) to maximize destruction of TI and at the same time to minimize reduction of soy protein solubility as well as loss of essential amino acids. However, this is easier to say than do. In fact, the amount of heat required to eliminate growth inhibitors in raw soybeans is sufficient to destroy cystine. (Rios-Iriarte and Barnes 1966). In actual situations, heat treatments do not completely inactivate all inhibitor activity. The possible adverse effects of residual inhibitors in soy products are largely unknown.
Adjunct treatment with various chemicals, including various thiol-containing compounds (such as cysteine, N-acetyl-cysteine, and glutathione) and sodium sulfite has been found to facilitate inactivation at lower temperatures (Liener 1994). Friedman and Gumbmann (1986) reported that the treatment of raw soy flour at 75xc2x0 C. with 0.03M sodium sulfite for 1 hr completely inactivated trypsin inhibitors, leaving no sulfite residue in the soy proteins. Their rat feeding tests showed that sulfite treatment is better than heat treatment alone in terms of nutritional improvement. However, any treatment of foods with chemicals should be viewed with caution with respect to regulatory issues.
Soybean is usually a single entity as a particular food, but soybeans are consumed in numerous forms, each of which has its own nutrient profile.
The soybean hull is also known as the seed coat. On a dry weight basis, hulls constitute about 8% of the total seed, depending on variety and seed size.
Dry soy hulls contain about 85.7% carbohydrates, about 9% protein, about 4.3% ash, and about 1% lipids. The fatty acid composition of hull lipids was recently found to be significantly different from those of cotyledons and hypocotyl axis (Liu et al. 1995b). For 6 genotypes tested, the average percentages plus or minus the standard deviation of major fatty acids for soy hulls are as follows: for palmitic acid, 23.2%xc2x13.0; for stearic acid, 14.8%xc2x12.5; for oleic acid, 14.9%xc2x13.4; for linoleic acid, 22.7%xc2x15.4; and for linolenic acid, 8.5%xc2x12.4. Soybean hulls also contain three plant sterols, campestrol, stigmasterol, and xcex2-sitosterol. Their rations were found to be 1:1.5:2 (Ibrahim et al. 1990).
There are at least three aspects regarding the significance of soy hulls. First, soy hulls affect the seed hydration rate prior to germination or processing. Second, soy hulls serve as valuable foodstuff. And third, soy hulls possess some potential as a source of dietary fiber and iron for human consumption. During imbibition (soaking) prior to germination or processing into various soyfoods, some soybeans, which are known as hard beans, do not absorb water or enlarge significantly. The occurrence of hard beans is an important defect because hard beans either fail to germinate or affect the quality of soy products. Regarding the water resistant mechanism of hard soybeans, Smith and Nash (1961) observed that the seed coat was the principal barrier to water imbibition and that hard beans usually were smaller and drier than those soybeans that imbibe normally. Saio (1976) examined hard beans by proximate analysis, light microscopy, and scanning electron microscopy and found that compared with normal beans hard beans had higher fiber and calcium content plus denser and tougher seed coats. He also found that the micropyle of hard beans is covered with outside pallisade cells. These data suggest that fiber and calcium content, seed coat surface and micropyle structure are related to water absorption of soybeans. Later, Arechavaleta-Medina and Snyder (1981) reasoned that the cuticle is most likely the site of the water barrier in the seed coat of soybeans because the soaking of hard beans in methanol or ethanol for 24 hr at 20xc2x0 C. made them permeable to water.
Soybean hulls are considered a by-product of soy processing. After separation from seeds during rolling or flaking, they are toasted and ground, then blended back with defatted soy meal to make a meal containing 44% protein. For a high protein (47-49%) meal, the hull is not blended in, but rather it is disposed of separately. At present, soy hulls are primarily used for animal feed. Since soy carbohydrates are mainly composed of xcex1-cellulose and hemicellulose, which are low in lignin, they are easily digested by animals. In fact, they are so highly digested that their digestible energy content is essentially equal to grains. In addition, when used in high forage diets, soy hulls eliminate the risk of acidosis (Klopfenstein and Owen 1988).
For the last two decades, some new uses of soy hulls have been explored, particularly including the use of soy hulls, with an emphasis as a source of human food. Like dietary fiber from other sources, soy hulls have been shown to reduce blood serum cholesterol levels (Mahalko et al. 1984). So, soybeans hulls have been used as a fiber supplement for bakery products at a level up to 10% (Johnson et al. 1985). Soy hulls are also rich in iron; approximately 32% of the total seed iron is in soy hulls (Levine et al. 1982). Thus, they can be used as a iron supplement for such foods as baked goods and breakfast cereals (Johnson et al. 1985, Lykken et al. 1987). In addition to hulls and cotyledons, the third structural part of the soybean seed is the hypocotyl axis, or germ. Upon germination, the axis will grow into a new soybean plant. By weight, the hypocotyl axis is about 2.0% of the seed. In general, the axis has a protein content similar to that of cotyledons but contains about 10% less fat and 10% more insoluble carbohydrate than the cotyledon part. After cracking the soybeans, during the first step of soybean processing, the axis may be separated with the cotyledon or with the hull, depending on which structural part it adheres to.
Recently, Liu et al. (1 995b) investigated the fatty acid composition of the axis and its relationship with the fatty acid composition of cotyledons. The seed axis has the lowest relative percentages of stearic and oleic acids and the highest of linoleic and linolenic acids. Furthermore, regardless of the great variation in the fatty acid profile of the whole seeds among six selected soybean genotypes, the ratio of the concentration of a particular fatty acid in the axis to the corresponding concentration in the cotyledon is, for each of five major fatty acids, highly conserved. The average of the ratio across the six genotypes for each of the five fatty acids is as follows: for palmitic acid, 1.38xc2x10.15; for stearic acid, 0.96xc2x10.11; for oleic acid, 0.27xc2x10.02; for linoleic acid, 1.17xc2x10.12; and for linolenic acid, 2.22xc2x10.22. This finding has two significant implications. First, it implies that lipid metabolism may be correlated in both the axis and cotyledon tissues during seed development. And second, with knowledge of the fatty acid composition of one tissue, one can predict that of the other. For example, if cotyledons are found to have 7.5% linolenic acid relative to total fatty acids from the tissue, the relative percentage of linolenic acid in the axis tissue would be around 16.7% (i.e., 7.5%xc3x972.22).
It has been speculated that the hypocotyl axis is the source of the beany flavor and undesirable taste in soy products. One explanation for this hypothesis is that the soybean hypocotyl has the highest percentage of polyunsaturated fatty acids (Liu et al. 1995b) and the highest concentration of isoflavones (Kudo 1991). This is corroborated by the fact that some soyfood processors have succeeded in reducing the off flavor in their products by removing the axis and hulls during processing (Tsukamoto et al. 1991).
Because of the low proportion of the hypocotyl axis in the whole seed and difficulty in separating it from the other parts commercially, relatively few studies have been conducted on its food value. However, this does not necessarily mean that the axis is insignificant. Considering the fact that isoflavone concentration in the hypocotyl is about 5-6 times higher than in cotyledons (Kudou 1991), there may be a potential for a new use of the soybean axis.
Soybeans contain both soluble and insoluble types of fiber. Soy fiber can help regulate gastrointestinal function and reduce cholesterol levels. Soluble fiber is known to affect the absorption of blood glucose in humans.
In Lancet 1979, (Stephen Holt, M. D., et. al.) showed that soluble fiber delayed the rate at which the human stomach emptied its contents into the small bowel, which is the site of maximal absorption of glucose. Soluble fibers are absorbed and promote the smoothing out of the levels of blood glucose following ingestion of soy fiber in the diet.
Studies have confirmed these effects of gel fibers (soluble fibers), which are found in soy beans and a variety of fruits, vegetables, and plants.
A study of obese patients with Type II diabetes, published in the American Journal of Clinical Nutrition in 1987, showed the benefit of soy fiber in regulating blood glucose levels. The subjects were first given a meal that did not contain soy fiber, then their blood glucose levels were measured. As is typical in diabetic individuals, glucose levels rose rapidly and stayed high for longer than normal following the meal. However, when the same patients consumed an identical meal to which 10 grams of soy fiber were added, blood glucose levels returned to normal more quickly. Other studies have confirmed these findings. In one clinical experiment, soy fiber and cellulose, an insoluble fiber found in bran and vegetables, were compared in relation to their effects on blood sugar. Those participants in the experiment given soy fiber had lower blood glucose levels over a three-hour period than the participants who received cellulose.
In addition, the fiber in soy food products helps promote a sense of fullness or satiety, which can be important for overweight diabetics, a group for whom weight loss is essential. Anyone who has tried to diet knows that a constant sense of hunger is detrimental and ultimately leads to overeating, usually followed by another period during which too little food is consumed. A person with diabetes mellitus cannot safely engage in this xe2x80x9csee-sawxe2x80x9d of deprivation followed by overeating. Stabilizing the balance of glucose and insulin is impossible without careful planning and a disciplined approach to diet. Therefore, a food that promotes a sense of satiety is of particular value in assisting weight loss where required.
The soluble fiber absorbs water and thus increases the water content. If a person does increase fiber intake, he or she will probably experience increased thirst. Drinking plenty of water promotes weight maintenance, healthy kidneys and regularity of the bowels. Portions of the ingested soy are fermented in the colon to produce short-chain fatty acids, which stimulate colonic activity, but the insoluble fiber found in soy does not make the stool too bulky.
The soluble fiber in soy may have a specific role in preventing colon cancer. This is a complex issue that involves the production of, and balance of, bacteria in the colon.
A half-cup of boiled soybeans contains almost half (about 44%) the recommended daily allowance (RDA) of iron and a significant amount of calcium magnesium, and zinc. Thiamine, niacin, riboflavin, and vitamin B6 are also present in amounts significant enough to consider soybeans a good source of these B-complex vitamins. Mature soybeans are not a source of vitamin C, but soybean sprouts are.
Soy isoflavones also function as antioxidants. In this role, they neutralize the effects of free radicals, which have the ability to damage cells and impair immunity. Antioxidants are believed to have a significant role in preventing cancer or retarding its growth. The indications that soy contains many valuable anti-cancer substances are so strong that it has become the subject of many cancer prevention studies.
Dr. Herman Adlercreutz, Professor in the Department of Clinical Chemistry at the University of Helsinki, has performed a great deal of research on the effect of soy derived materials such as the effect of soy isoflavones on the maintenance of prostate health. Laboratory experiments with cultures of prostate cancer cells show an anti-tumor effect of soy isoflavones, and several animal studies have shown that transplanted prostate cancer in animals can have its growth retarded by genistein (a principal soy isoflavone).
Current research and clinical experience is leading more and more health care practitioners to recommend that mature men add at least two servings of soy food products to their daily diet. In addition, isoflavone supplements are available to both prevent and treat benign prostatic enlargement and possibly cancer of the prostate. Beneficial effects of high isoflavone intake have been reported in advanced prostate cancer, including reversal of symptoms of benign prostate hyperplasia with just modest intake of soy isoflavones.
Quaffing a soy drink containing isoflavones lowers total and LDL cholesterol levels by 5%-10% in moderately hypercholesterolemic men and women.
The results of a new double blind randomized controlled trial clearly demonstrate that it is the soy isoflavones, not soy protein, which are responsible for this cholesterol-lowering effect, as reported by Dr. John R. Crouse III at the Annual Conference on Cardiovascular Disease Epidemiology and Prevention sponsored by The American Heart Association.
A diet including 20 g of soy protein per day provides about 34 mg of isoflavones. Based on aggregate data, the FDA has suggested 25 g/day of soy protein as an effective and palatable consumption level.
A number of isoflavone supplements are widely available, but it remains unestablished whether these phytonutrients are as effective as whole soy proteins, which contain saponins and other nutrients.
The presence of saponins in the yellow soybean and soy beverages made therefrom is intriguing. Saponins may promote reduction of blood cholesterol, inhibit the formation of cancer, and also may help prevent heart disease. These phytochemicals may also have a role in promoting weight reduction and may also promote a reduction in the effects of aging.
The instant invention provides a method of preparing a texturized soy beverage which promotes weight loss and additionally provides ameliorative benefits as an adjunct to treatment of cardiovascular disease, type II diabetes mellitus, hypertension, dyslipidemia, osteoporosis, Alzheimer""s disease, breast cancer uterine cancer, colon cancer, prostate cancer and kidney disease.
The texturized soy beverage of the instant invention provides a nutritional supplement which contains high amounts of soy protein, phyto-nutrients, both soluble and insoluble types of fiber and contains beneficial types of fats, such as omega-3 and omega-6 fatty acids. Furthermore, one serving of SAPONIN WHITE(trademark) soy beverage, prepared as described hereinbelow, contains 14.3 g of soy-protein and phytonutrients.
The fiber in the texturized soy beverage helps promote a sense of fullness or satiety, which can be beneficial for overweight and obese individuals in the promotion of weight loss.
Patients, after ingesting the texturized soy beverage prepared according to the invention, become thirsty and drink increased amounts of water. The higher intake of water promotes weight maintenance, promotes regularity of the bowels, and promotes healthy kidneys. In addition, soluble fiber in the texturized soy beverage absorbs water after ingestion and thus increases the water content.
The texturized soy beverage of the invention, SAPONIN WHITE(trademark), when administered as a nutritional supplement for the promotion of weight loss, has no complication of constipation and promotes negative proteinuria.
In an embodiment of the invention, the texturized soy beverage suitable for human consumption is prepared according to the following method:
providing clean whole soybeans having their outer hulls;
combining the soybeans with water sufficient to cover the soybeans to form a first mixture and allowing the soybeans to soak in the water in an approximately 2xc2x0 C. temperature environment for between approximately eight and approximately ten hours;
adding additional fresh water to the first mixture to form a second mixture and placing in a cooking vessel, having a lid, a third mixture comprising said soybeans and a sufficient portion of water from the second mixture to cover the soybeans in said cooking vessel;
covering the cooking vessel with the lid and placing a heat source in thermal communication with the cooking vessel to cook the soybeans until a foam accumulates inside the cooking vessel and the foam contacts the lid of the cooking vessel;
separating the cooking vessel from the heat source and keeping the cooking vessel covered with the lid for at least 2 minutes;
removing the lid from the cooking vessel, separating the water from the soybeans, and drying the soybeans;
forming a fourth mixture by blending 1 part by volume of the soybeans with between xc2xd part and 2 parts by volume of a material selected from the group comprising fat-free milk, fruit and vegetables;
wherein the fourth mixture is blended such that at least some of the soybeans in said fourth mixture remain in small pieces of sufficient size, preferably between 0.023 and 0.3 inches in size, such that the small pieces of soybean may be chewed before being swallowed.
This procedure of the invention may cause metabolic changes or biochemically alter some substance in the texturized soy beverage so as to promote improved kidney function.
It has been discovered that whole soybeans may be rendered palatable while providing high nutritional value by preparing the texturized soy beverage product according to the invention.
The SAPONIN WHITE(trademark) texturized soy beverage of the instant invention, in one serving, contains 14.3 g of soy protein, almost half (about 44%) of the recommended daily allowance of iron, and also a significant amount of calcium, magnesium, zinc, thiamin, niacin, riboflavin and vitamin B6. Preferably the texturized soy beverage of the instant invention is consumed in sufficient quantity to provide the FDA-suggested amount of 25 g per day of soy protein. More preferably, the texturized soy beverage of the instant invention is consumed such that isoflavones are ingested at a rate of at least approximately 30 to 40 mg/day.
The fiber in the texturized soy beverage of the instant invention helps promote a sense of fullness or satiety, induces thirst, and promotes the drinking of increased amounts of water. The higher intake of pure water is promotes weight maintenance, promotes regularity of the bowels, and promotes maintenance of healthy kidneys.
The general recommendation that everyone consume daily 6 to 8 eight ounce glasses of water is especially important for stone-forming persons or for others whom are at risk for dehydration.
The texturized soy beverage in accordance with the instant invention provides soy in the form of texturized vegetable protein drink which is known by the tradename SAPONIN WHITE(trademark). Because it is filling and satisfying, rich in the basic nutrients of protein, carbohydrates without starches, and fat, and because it can be prepared according to the invention in a great variety of forms, a texturized soy beverage nutritional supplement according to the invention is the perfect dieter""s beverage.
The present invention provides a process for preparing a nutritive composition for use in a weight loss program comprising the steps of soaking clean whole soybeans in water at a low temperature for several hours, rinsing the beans and placing beans with sufficient water to cover the beans in a cooking vessel, heating the beans in the cooking vessel while covered by exposing the cooking vessel to a heat source until foam accumulates inside the cooking vessel, removing the heat source from the cooking vessel and keeping the cover on the cooking vessel for a period of at least 2-3 minutes, then draining the soybeans, adding fat-free milk, fruit or vegetables and blending to form a mixture which contains some solid soybean particles, preferably having sizes greater than approximately 0.023 inches and more preferably having sizes in the range of approximately 0.023 inches to approximately 0.3 inches.
The blended soy composition preferably contains a water soluble component of soybean derived materials and variously sized solid soybean particles (particularly soybean particles having sizes in the range from around 0.023 to 0.3 inches) which provided the texturized characteristics of the texturized soy beverage of the invention. The amount and distribution of these solid particles sizes may vary depending on the blending time. Neither a disintegrator nor a screen or filter need be used. Therefore, the presence of solid soybean particles is ensured. The composition, when consumed, promotes weight loss, weight management and receipt of proper nutrition.
In further embodiments of the invention, methods are provided for preparing the above-described soybean-based composition combined with fruits and vegetables to provide improved flavor, fiber, nutritional benefits, or patient acceptance.
The following Tables 1-5 illustrate the comparative nutrient and isoflavone content of cooked soybeans, various soymilks, cow""s milk, human breast milk. The texturized soy beverage in accordance with the instant invention differs essentially from soymilks in that it contains chewable soybean particles, preferably between 0.023 and 0.3 inches in size, which provide texture, promote chewing, greater consumption of water, and weight loss and weight maintenance and other benefits when ingested.